1. The most important thing about buying a new bike is to make sure it fits. The only way you'll know if the bike is right for you is to size up the bike and make sure that the bike's geometry matches your body's geometry. Ask questions and do some research.
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2. If possible, try to find a shop that will let you demo the bike on real dirt. Five minutes in a parking lot won't cut it. You wouldn't buy a car without a real world test drive, and a bike should be no different.
3. Don't belive the hype. Just because your favorite rider or best friend rides a certain bike, that doesn't mean that's the best one for you. Have an open mind and be realistic about your needs and ability.
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  1. #1
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    What am I doing wrong?

    I just bought a new GT Agressor today and took it out on a trail. While I was on the trail I was struggling to shift the bike. I would be pedaling and shift and it seemed like nothing was happening. It sounded like it was trying to move the chain but it just wasn't doing it. I got the bike home and lifted the back up and pedaled it with my hands and tried to shift it and it worked like a champ. What am I doing wrong while I am riding?

  2. #2
    Fat-tired Roadie
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    Two things.

    Sometimes bikes shift a little differently with a rider on them. Use your barrel adjusters to fine-tune it while you're riding.

    Shifting doesn't work as well under load. Different drivetrains tolerate different amounts of load during a shift. But you might try putting a little less tension on your chain during shifts. This is especially important for shifting the front.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  3. #3
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    Quote Originally Posted by AndrwSwitch View Post
    Two things.

    Sometimes bikes shift a little differently with a rider on them. Use your barrel adjusters to fine-tune it while you're riding.

    Shifting doesn't work as well under load. Different drivetrains tolerate different amounts of load during a shift. But you might try putting a little less tension on your chain during shifts. This is especially important for shifting the front.
    This seems like my issue. Now that I think about it I was trying to shift the front gear while I was already going uphill. Is the only way of fixing this shifting before I get to a hill?

  4. #4
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    Unfortunately when you are sold a bike most shops don't explain the basics. You are right, you need to shift before the hill, or learn to push/pause to reduce the chain tension. BITD before shift ramps that is how you had to make shifts. Like a stick shift withou a clutch.

    That said, going from middle to small chainring is a lot easier and quicker. Usually the issue happens with the cassette in trying to cram the chain onto the big cog.

    Couple of things you can do... run in the small chainring and go a little slower and then practice the shifting on flatter ground so you develop a rhythm.

    John
    1995 Trek 970 - 80mm Atom Race
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  5. #5
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    Question:

    Did you buy your bike from a small shop, or from a big box store? If from a big box store, consistency on bike setup can be terrible and builds can be pretty poor. It may need a tune up before it even leaves the store. If from a small shop, usually more care is put into builds (but that does vary from shop to shop, too).

    Shifting under load will definitely make your drivetrain seem like it's out of adjustment, too. Dumping a lot of gears at once (shifting way too late) can make it seem even worse. Downshift before you REALLY need it and do so gradually.

  6. #6
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    Quote Originally Posted by NateHawk View Post
    Question:

    Did you buy your bike from a small shop, or from a big box store? If from a big box store, consistency on bike setup can be terrible and builds can be pretty poor. It may need a tune up before it even leaves the store. If from a small shop, usually more care is put into builds (but that does vary from shop to shop, too).

    Shifting under load will definitely make your drivetrain seem like it's out of adjustment, too. Dumping a lot of gears at once (shifting way too late) can make it seem even worse. Downshift before you REALLY need it and do so gradually.
    I bought it from a small local shop and they seemed like they knew what they were doing. They have a full repair shop so I can't imagine it is set up wrong. That being said I know nothing about how it should be set up.

  7. #7
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    Now that I think about it I was trying to shift the front gear while I was already going uphill. Is the only way of fixing this shifting before I get to a hill?
    Speed and momentum are your friends. Rather than shift before you start up the hill, stay in the gear you are in and ride hard and fast up the start of hill. Well before you run out of momentum and power, take the pressure off the pedals, and drop to a smaller ring.

    As you ride more and get in better shape, you will be riding fast enough so that you can coast a short distance, allowing you to shift on all but the steepest hills. Yeah, on some climbs you have to get in the right gear before you start up and stay in that gear until you get to the top, but they are the exception around here at least.

    As others have said, you can shift with some tension on the chain with some equipment. But learn to coast and shift quickly and you're covered. Then you can experiment with shifting under load.

  8. #8
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    Quote Originally Posted by epwna View Post
    I bought it from a small local shop and they seemed like they knew what they were doing. They have a full repair shop so I can't imagine it is set up wrong. That being said I know nothing about how it should be set up.
    Just take it back to the store and ask them to check it out. Sounds like something is wrong with the set up to me.

  9. #9
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    If you shift when the cranks are in the 12/6 position, the change is usually smoother and instant. There should never be a grind as you shift. You can change while climbing, but try to spin a bit faster before and back off the power as you do shift.

  10. #10
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    When I have to down shift while climbing, I try to gain some momentum and then slow my stroke as I shift til it's in, then hit it again. Kinda like shifting a car.. You're not gonna keep the rpm at 4500 steady while charging gears

    Sent from my 831C using Tapatalk

  11. #11
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    Make sure you’re not trying to shift into a cross-chain combination i.e. dropping into your small ring while the chain is down on the smaller end of the cassette sprockets. Many drivetrains, regardless of how well they are adjusted, tend to resist shifting crisply into these combos, especially under load. And you really shouldn’t be using cross-chain combos anyway.

  12. #12
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    Quote Originally Posted by ou2mame View Post
    When I have to down shift while climbing, I try to gain some momentum and then slow my stroke as I shift til it's in, then hit it again.
    ^^^ This!

  13. #13
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    Quote Originally Posted by epwna View Post
    This seems like my issue. Now that I think about it I was trying to shift the front gear while I was already going uphill. Is the only way of fixing this shifting before I get to a hill?
    yes...choose front ring before an uphill grade with constant load

    shifting front while in a climb can result in busting the chain open or some other failure/chain jam

    it can be done but you need to sprint a bit ahead, so you can essentially coast a few feet uphill and shift gently

    new chains and modern expensive chainrings are cut and ramped and can handle some degree of powered front shifting but it is never advisable on a climb

  14. #14
    Fat-tired Roadie
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    Oh, I don't think it's as bad as all that. It does take a little finesse and timing, but I drop a gear during a climb from time to time. I really only need to take the pressure off the crank for about a quarter turn.
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  15. #15
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    What Andrew said, you just need to take pressure off the chain .

  16. #16
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    I think the best method involves shifting before and during the climb. If a section is steep enough to rob be of momentum, I shift into the gear in which I can spin the fastest, a second or so before the climb starts. When you are spin at 60 rpm, front shifts take less than a second. I attack the hills at a faster spin, and shift down as I near 60. Shifting at the cassette s prefered, so I make sure I trade chainrings for cogs before the climb if the gearing is available.

    Less than a second per shift, no pressure on the pedals, can even do this when on the granny ring and grabbing the last remaining cog while fighting to keep the front end down. Takes a bit of practice to perfect those last three gears on a crazy climb, but it can be done with a bit of trial and error.

  17. #17
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    It saddens me to say that this "advanced" technique is no longer one I need, being as I now ride with a single chainring

    The reason chains get damaged and gears don't change is not just cable stretch or load (power through the crank), but chainline. If you are trying to shift under load, a cross-chain line will battle against you and maybe damage the chain.

    Rather than shift early, or climb, then accelerate and shift by reducing the load as suggested above, try this:

    Stay in your "chosen" gear for where you are. As you hit the climb, creek crossing, reverse grade, G-out etc, get your balance and drop the front chainring. That gives you the equivalent of 2 rear cogs without increasing the chain tension. If the terrain change is really brutal, you can push the rear derailleur one more gear down also without increasing the chain tension.

    It's no different to starting down a big hill - dropping one rear cog and increasing one front chainring gives you 3 extra gears to catch up with the acceleration - just in reverse!

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